#ifndef STK_MESH2D_H
#define STK_MESH2D_H

#include "Instrmnt.h"
#include "OnePole.h"

namespace stk {

/***************************************************/
/*! \class Mesh2D
    \brief Two-dimensional rectilinear waveguide mesh class.

    This class implements a rectilinear,
    two-dimensional digital waveguide mesh
    structure.  For details, see Van Duyne and
    Smith, "Physical Modeling with the 2-D Digital
    Waveguide Mesh", Proceedings of the 1993
    International Computer Music Conference.

    This is a digital waveguide model, making its
    use possibly subject to patents held by Stanford
    University, Yamaha, and others.

    Control Change Numbers:
       - X Dimension = 2
       - Y Dimension = 4
       - Mesh Decay = 11
       - X-Y Input Position = 1

    by Julius Smith, 2000 - 2002.
    Revised by Gary Scavone for STK, 2002.
*/
/***************************************************/

const unsigned short NXMAX = 12;
const unsigned short NYMAX = 12;

class Mesh2D : public Instrmnt {
public:
  //! Class constructor, taking the x and y dimensions in samples.
  Mesh2D(unsigned short nX, unsigned short nY);

  //! Class destructor.
  ~Mesh2D(void);

  //! Reset and clear all internal state.
  void clear(void);

  //! Set the x dimension size in samples.
  void setNX(unsigned short lenX);

  //! Set the y dimension size in samples.
  void setNY(unsigned short lenY);

  //! Set the x, y input position on a 0.0 - 1.0 scale.
  void setInputPosition(StkFloat xFactor, StkFloat yFactor);

  //! Set the loss filters gains (0.0 - 1.0).
  void setDecay(StkFloat decayFactor);

  //! Impulse the mesh with the given amplitude (frequency ignored).
  void noteOn(StkFloat frequency, StkFloat amplitude);

  //! Stop a note with the given amplitude (speed of decay) ... currently
  //! ignored.
  void noteOff(StkFloat amplitude);

  //! Calculate and return the signal energy stored in the mesh.
  StkFloat energy(void);

  //! Input a sample to the mesh and compute one output sample.
  StkFloat inputTick(StkFloat input);

  //! Perform the control change specified by \e number and \e value (0.0 -
  //! 128.0).
  void controlChange(int number, StkFloat value);

  //! Compute and return one output sample.
  StkFloat tick(unsigned int channel = 0);

  //! Fill a channel of the StkFrames object with computed outputs.
  /*!
    The \c channel argument must be less than the number of
    channels in the StkFrames argument (the first channel is specified
    by 0).  However, range checking is only performed if _STK_DEBUG_
    is defined during compilation, in which case an out-of-range value
    will trigger an StkError exception.
  */
  StkFrames &tick(StkFrames &frames, unsigned int channel = 0);

protected:
  StkFloat tick0();
  StkFloat tick1();
  void clearMesh();

  unsigned short NX_, NY_;
  unsigned short xInput_, yInput_;
  OnePole filterX_[NXMAX];
  OnePole filterY_[NYMAX];
  StkFloat v_[NXMAX - 1][NYMAX - 1]; // junction velocities
  StkFloat vxp_[NXMAX][NYMAX];       // positive-x velocity wave
  StkFloat vxm_[NXMAX][NYMAX];       // negative-x velocity wave
  StkFloat vyp_[NXMAX][NYMAX];       // positive-y velocity wave
  StkFloat vym_[NXMAX][NYMAX];       // negative-y velocity wave

  // Alternate buffers
  StkFloat vxp1_[NXMAX][NYMAX]; // positive-x velocity wave
  StkFloat vxm1_[NXMAX][NYMAX]; // negative-x velocity wave
  StkFloat vyp1_[NXMAX][NYMAX]; // positive-y velocity wave
  StkFloat vym1_[NXMAX][NYMAX]; // negative-y velocity wave

  int counter_; // time in samples
};

inline StkFrames &Mesh2D ::tick(StkFrames &frames, unsigned int channel) {
  unsigned int nChannels = lastFrame_.channels();
#if defined(_STK_DEBUG_)
  if (channel > frames.channels() - nChannels) {
    oStream_
        << "Mesh2D::tick(): channel and StkFrames arguments are incompatible!";
    handleError(StkError::FUNCTION_ARGUMENT);
  }
#endif

  StkFloat *samples = &frames[channel];
  unsigned int j, hop = frames.channels() - nChannels;
  if (nChannels == 1) {
    for (unsigned int i = 0; i < frames.frames(); i++, samples += hop)
      *samples++ = tick();
  } else {
    for (unsigned int i = 0; i < frames.frames(); i++, samples += hop) {
      *samples++ = tick();
      for (j = 1; j < nChannels; j++)
        *samples++ = lastFrame_[j];
    }
  }

  return frames;
}

} // namespace stk

#endif
